Estimates of Natural and Unimpaired Flows for the Central Valley of California: Water Years 1922-2014 (draft)

California Department of Water Resources (DWR) | March 1st, 2016

Estimating regional water supplies that would have occurred absent human activities is a common practice in water resources planning. In this report, such theor

Estimating regional water supplies that would have occurred absent human activities is a common practice in water resources planning. In this report, such theoretical water supply estimates are referred to as “unimpaired” flow. Since 1980, the Department of Water Resources (Department) has periodically published estimates of Central Valley unimpaired flows. In spite of the Department’s previous attempts to distinguish between natural conditions and its calcula tion of theoretical unimpaired flows, unimpaired flow estimates have frequently been used as a surrogate measure of natural conditions, presumably because natural flow estimates were unavailable. A major objective of this report is to clarify the conceptua l differences between natural and unimpaired flows. In this report, the term “unimpaired” flow is used to describe a theoretically available water supply assuming existing river channel conditions in the absence of (1) storage regulation for water supply a nd hydropower purposes and (2) stream diversions for agricultural and municipal uses. Unimpaired flow estimates are theoretical in that such conditions have not occurred historically. In pristine watersheds which have undergone little land use change, unim paired flow estimates provide a fixed frame of reference to develop relationships between precipitation, runoff, and water supply based on long - term hydrologic records. For many years these relationships were based on the assumption of stationarity, i.e. that the past is a good indicator of the future. However, global warming now requires hydrologists and water resources managers to analyze non-stationary processes, requiring more sophisticated tools and techniques to quantify future water supplies. This report updates and extends the Department’s previous published estimates of unimpaired flows for 24 Central Valley sub-basins and the Delta. Monthly unimpaired flows are presented for water years 1922 - 2014.

Estrogen Receptor In Vitro Assay Linkage Studies

San Francisco Estuary Institute (SFEI) | July 30th, 2018

Our Phase 1 study indicated that it would be possible to link in vitro ER assays to in vivo endpoints (Mehinto et al. 2018). These conclusions were based on several expe

Our Phase 1 study indicated that it would be possible to link in vitro ER assays to in vivo endpoints (Mehinto et al. 2018). These conclusions were based on several experiments that were performed at the University of Florida and SCCWRP. Our conclusion was that in order to see higher order effects in Menidia, the dose of estrogens in the in vivo assay needed to be above the EC50 point for the in vitro assays. However, the dose response curve for the in vivo endpoints was broad starting at 20 ng E2/L and progressing to 20, 200 and 500 ng/L. Our Phase 1 experiments did not include the resolution to reduce uncertainty in estimated quantitative in vitro to in vivo linkage factors. While the data allowed us to extrapolate those values, it was decided that the experiment should be repeated another time with more intervening estradiol concentrations, to get a better determination. A second goal of the study was to measure estrogen equivalencies at 6 locations in San Francisco Bay, testing both the water and sediments, to determine the usefulness of the approach. Results from this study will begin to enable managers to determine whether or not additional cleanup is necessary for treated effluents that are disposed into sensitive estuarine environments.

Estuarine Habitat Use by White Sturgeon (Acipenser transmontanus)

University of California, Davis (UC Davis) | December 1st, 2020

White Sturgeon (Acipenser transmontanus), a species of concern in the San Francisco Estuary, is in relatively low abundance because of a variety of factors. The purpose o

White Sturgeon (Acipenser transmontanus), a species of concern in the San Francisco Estuary, is in relatively low abundance because of a variety of factors. The purpose of our study was to identify the estuarine habitat used by White Sturgeon to aid in the conservation and management of the species locally and across its range. We seasonally sampled sub-adult and adult White Sturgeon in the central estuary using setlines across a habitat gradient representative of three primary structural elements: shallow wetland channel (mean sample depth = 2 m), shallow open-water shoal (mean sample depth = 2 m), and deep open-water channel (mean sample depth = 7 m). We found that the shallow open-water shoal and deep open-water channel habitats were consistently occupied by White Sturgeon in spring, summer, and fall across highly variable water quality conditions, whereas the shallow wetland channel habitat was essentially unoccupied. We conclude that sub-adult and adult White Sturgeon inhabit estuaries in at least spring, summer, and fall and that small, shallow wetland channels are relatively unoccupied.

Estuary News, April 1993

Publisher not available | April 15th, 1993

Estuary News, April 1994

San Francisco Estuary Partnership (SFEP) | April 15th, 1994

Estuary News, April 1995

San Francisco Estuary Partnership (SFEP) | April 15th, 1995

Estuary News, April 1996

San Francisco Estuary Partnership (SFEP) | April 15th, 1996

Estuary News, April 1997

San Francisco Estuary Partnership (SFEP) | April 15th, 1997

Estuary News, April 1998

San Francisco Estuary Partnership (SFEP) | April 15th, 1998

Estuary News, April 1999

San Francisco Estuary Partnership (SFEP) | April 15th, 1999